1. Technical Field
The present invention relates to a technique for improving the moving-image display characteristic of an electrooptic device that employs what is called an area scanning drive system.
2. Related Art
Projectors are becoming widely used which form reduced images using an electrooptic device such as a liquid crystal device and which project the reduced images on enlarged scale with an optical system. Such electrooptic devices that form reduced images have the problem of so-called disclination (inferior orientation) because of the extremely narrow gap between the pixels. The disclination can be prevented by plane inversion (also referred to as frame inversion) in which adjacent pixels are given the same polarity. However, the plane inversion has the problem of causing a difference in display between the upper end and the lower end of the display screen.
To solve the problem of display difference, what is called an area scanning drive system has been proposed in which positive potential and negative potential are applied in the period of one frame, and areas to which the different potentials are written continue in the row direction so that the proportion of the pixels held at positive polarity to the pixels held at negative polarity in one column is one to one at any timing (see JP-A-2004-177930).
In the area scanning drive system, however, the same display content is maintained during one frame because both the positive and negative voltages provide the same display content although polarities are different. This increases the persistence of vision to cause the outline of moving areas to blurs thus posing the problem of low moving-image display characteristic. Such a problem of low moving-image display characteristic is not limited to the area scanning drive system but also occurs in display devices having a hold-type display characteristic such as liquid crystal displays.